1. Field of the Invention
The present invention relates to an arrangement for manufacturing book blocks formed of printed sheets which are bound by an adhesive. The arrangement includes a spiral guide wall for transferring the gathered printed sheets which are placed one on top of the other in stacks from an essentially horizontal position into a vertical position. The arrangement further includes a support element which projects at approximately a right angle from a lower edge of the guide wall for guiding the stacks at the rear folded edges of the printed sheets and a guide duct formed by a guide rail which is adjustable in accordance with the height of the stacks.
2. Description of the Related Art
As is well known, the various printed sheets are gathered into loose stacks in a gathering machine composed of a plurality of feeders or loaders arranged in a row. The printed sheets are usually placed by the feeders or loaders one on top of the other in the collecting duct of the gathering machine with the rear folded edges of the printed sheets forming the back of the book block to be produced being first, and the printed sheets are collected in the correct sequence into a complete loose book block.
For this purpose, the collecting duct of the gathering machine may have a slightly inclined flat position.
The collecting duct of the gathering machine is followed by a conveying duct which is the subject of the present invention. The same conveying device with drive members is provided for the conveying duct as for the collecting duct.
In the conveying duct, also called transfer duct, the stacks are transferred from an approximately horizontal position into a vertical position by being guided along a spiral guide wall and a support element which projects from the lower edge of the guide wall and guides the stacks at the rear folded edges of the printed sheets.
In order to prevent the stack from falling over, a guide rail is provided on the side of the stack located opposite the spiral guide wall. The guide rail is constructed so as to be adjustable in accordance with the height of the stack.
In the known arrangement, since the conveying duct, and particularly the support element, have a twisted shape and since the guide rail is adjustable, it is impossible to prevent the formation of a slot-like gap between the support element and the guide rail over the entire length of the conveying duct. This situation may negatively affect the conveyance of the stacks.
For example, the printed sheets sliding along the guide rail may be clamped with the rear folded edges into the slot-like opening and may be held back which, among other problems, would interrupt the manufacturing process.
This effect is reinforced by the pressure applied on the book block to hold the book block together.
The formation of recesses acting in the manner of a wedge cannot be prevented by dividing the guide rail into shorter sections along the support element.